Thin stillage and distillers' grains are byproducts remaining after alcohol distillation from a fermented cereal grain mash. Both byproducts are used as energy and protein sources for ruminants. There are two main sources of these byproducts. The traditional sources were from brewers. However, more recently, ethanol plants such as corn, sugar cane, cassaya and potatoes have become a growing source.
DDGS contain valuable bio-materials mainly fibers, oil and protein. The oil in DDGS could be used either as cooking oil or as a biofuel. The main protein in corn is Zein which has been used in the manufacture of a wide variety of commercial products, including coatings for paper cups, soda bottle cap linings, clothing fabric, buttons, adhesives, coatings and binders, recently this protein has been used as a coating for candy, nuts, fruit, pills, and other encapsulated foods and drugs. Additionally Zein can be further processed into resins and other bioplastic polymers. Fibers may be used as raw materials in the production of lignocellulosic ethanol. Residue materials from ethanol production contain fibers from which ethanol has been extracted. However, only about 50-70% of the ethanol in these materials is typically extracted leaving substantial portion of ethanol that is available for further extraction. Tables 1 and 2 provide a typical content breakdown of the various materials in DDGS.
TABLE 1Cellulosic biomass compositional analysis of DDGS.AverageDry matter88.8Water extractives24.7Ether extractives11.6Crude protein24.9Glucan (total)21.2Cellulose16Starch5.2Xylan and Arabinan13.5Xylan8.2Arabinan5.3Ash4.5Total dry matter100.4
TABLE 2Nutritional Compositional analysis of DDGS.Nutritional Compositional analysisDry matter88.9Crude protein27.3Crude fat14.5Carbohydrates53.5Ash4.7Total100
It would therefore be desirable to provide a process to separate these materials in order to maximize their uses.